1. Field of the Invention
The present invention relates to firefighting equipment and, more particularly, to an aerial-delivered fire retardant device.
2. Background of the Invention
In the western United States, wildfires cause widespread destruction of nature, buildings, and lives. Billions of dollars are spent annually on wildfire suppression. Because even a small wildfire can overwhelm typical structural firefighting equipment, air-based resources are often brought to bear, including fixed- and rotary-winged aircraft. Fixed-wing aircraft must make a pass over the wildfire and drop water or retardant like a bomber. Helicopters can hover over the fire and drop water or retardant. However, each aircraft is “committed” to release their entire fire suppressant load at one time, and must leave the scene for reloading. In addition, aircraft must fly dangerously close to the fire to drop their payload, for example, about 500 feet above ground level.
Common materials used to fight wildfires include water and fire retardants. Water is usually dropped directly on flames because its effect is short-lived. Fire retardants are typically dropped ahead of the moving fire or along its edge and may remain effective for two or more days. Currently, fire retardants are typically applied in liquid or semi-liquid form. Present retardants include ammonium sulfate, diammonium sulfate, diammonium phosphate, ammonium polyphosphate, or monoammonium phosphate. These retardants are less toxic than sodium or boron salts, which can sterilize the ground or make regrowth difficult. These retardants also act as fertilizers to help the regrowth of plants after the fire. However, such fire retardants can be complex mixtures of chemicals to facilitate its efficacy. For example, fire retardants often contain wetting agents, preservatives, thickeners, rust inhibitors, and coloring agents. Examples of coloring agents are ferric oxide (red) or fugitive color to mark where they have been dropped. Thickeners include attapulgite clay, or a guar gum derivative, and are used to prevent dispersal of the retardant after it is dropped from the plane. Brand names of aqueous fire retardants for aerial application include Fire-Trol® and Phos-Chek®. Fire-Trol® aerial fire retardants are available from Fire-Trol Holdings, LLC, Phoenix, Ariz. Phos-Chek® aerial fire retardants are available from ICL Performance Products in Ontario, Calif. Class A foams also may be used as fire retardants. Class A foams lower the surface tension of the water, which assists in the wetting and saturation of Class A fuels with water. This can aid fire suppression and can prevent re-ignition. However, foams tend to be short-lived suppressants.
Nevertheless, aqueous fire-fighting materials can be problematic. Water, while inexpensive, can be difficult to reach and to deliver in remote areas or in treacherous terrain. Also, without a thickener or wetting agent, water tends to runoff very quickly and be absorbed into a small area of soil. Water is heavy, weighing approximately 8 pounds per gallon. Thousands of gallons of water, or more, are used even in a small wildfire. As aqueous mixtures, fire retardants can be heavy, like water, but they also are expensive and more finite in quantity. What is needed is a biologically-friendly, plentiful, lightweight, fire retardant, which can be easily delivered from a safe distance, even in remote or dangerous conditions.